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Growing Innovation: Issue 7, May 20, 2016

Macadamia growers join forces to tackle the destructive fruitspotting bug

In an effort to quash the effects of a pest damaging tropical tree and vine, Hort Innovation, NSW DPI, DAF and other collaborators have joined forces with growers to explore management techniques for the much maligned fruitspotting bug.

The five year, multi-industry initiative involving the macadamia, avocado, papaya, lychee, custard apple and passionfruit industries, investigated a multi-target approach to fruitspotting bug management including cultural, biological and chemical control methods.

A key approach was Area Wide Management (AWM) where trap hedges using alternative host of fruitspotting bugs, particularly of Murraya paniculata to draw the bug into specific areas for monitoring and management. A grower driven AWM program on macadamia farms along Connor Road in Alstonville saw growers synchronise their strategies with some expert input from the NSW DPI Project team.

Chair of the Connor Road Macadamia Growers Group, grower Hugh Harris, said that the AWM brought together growers, NSW DPI and consultants.

Mr Harris said: “Our involvement in this project saw growers collaborating with each other and experts to drive research outcomes which are critical in targeting such a destructive pest in our region.

“As part of the AWM we met regularly to discuss ideas and implement joint monitoring and treatment strategies. This provided very useful information and allowed us in many cases to refine our monitoring program and parameters to make a spray decision.

“We are working as a collective towards reducing the number of spray applications required by implementing additional monitoring techniques.

To date, a single-targeted approach, namely broad-spectrum insecticides, has been the only management option for growers. This approach is not sustainable in the long-term and a multi-targeted approach was required to be investigated.

“This kind of research is critical in macadamia production, particularly as we are seeing more pests and pest activity in the orchards over recent years. Also, fewer, less effective chemical control options are available for use in the orchards.

“It is very important that as growers we gain a better understanding of the life cycles of the various insect and other pests and how they inhabit the orchards and inflict damage to the crops.

“If we can better understand these and be more coordinated in our control regime we can work towards reducing the number of spray applications required. This has many benefits including reducing insecticide resistance, lesser environmental impact and the cost of chemicals and application.”

Fruitspotting bugs are a major impediment to the successful production of most tree fruits and nuts and some vine fruits through the coastal and sub-coastal areas of tropical and sub tropical Australia.

They can cause significant damage, predominantly manifested as spots or cracks on developing or mature fruit, or as splits, water-soaked marks or wilting in vegetative crops. Losses to fruitspotting bugs are difficult to quantify accurately but could amount to tens of millions of dollars annually.

For the Australian macadamia industry, the economic impact of fruitspotting bugs is estimated at $8.975 million per annum (Starkey, unpublished data).

“We suffered some crop loss as a result of fruitspotting bug. The main contributor to this was probably a lack of understanding of the critical timing of treatment such as spraying and the physical constraints sometimes involved in treatment such as weather conditions and neighbour considerations. It is difficult to put a number of it, but I am sure our yield and quality has been impacted.

“We are all in the same boat, so working collaboratively with peers as well as experts, will lead us to outcomes quicker.”

A spider is beneficial in managing the fruitspotting bug as seen in this video.

The project has been funded by R&D levies from the Avocado, Macadamia, Lychee, Papaya, Passionfruit and Custard Apple industries, with additional funding via the Across Industry Committee and matched by the Australian Government through HAL. NSW Department of Primary Industries (NSW DPI) and Queensland Department of Agriculture and Fisheries (QDAF) are also contributing in-kind funds to the project, and NSW DPI is managing the project on behalf of all partners. Other project partners include the University of Queensland, Australian Centre for International Agricultural Research (ACIAR).

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